Electrical Sensor With Configurable Settings

ABSTRACT

An electrical sensor is described. The electrical sensor including an electrical signal input configured to receive an electrical signal, an alarm, one or more inputs configured to set a configuration value corresponding to one or more indicators on the electrical sensor, and monitor. The monitor is coupled with the electrical signal input, the alarm, and the one or more inputs. Further, the monitor is configured to determine a characteristic of the electrical signal received on the electrical signal input. And, the monitor is configured to activate the alarm based on the configuration value set by the one or more inputs and the characteristic of the electrical signal.

FIELD

Embodiments of the invention relate to electrical sensors. Inparticular, embodiments of the invention relate to electrical sensorsthat can be configured.

BACKGROUND

Electrical sensors are used to detect and monitor one or morecharacteristics of an electrical signal in a conductor. As such,electrical sensors can be used in systems to monitor current levels,voltage levels, power levels, or other aspects of an electrical system.Monitoring one or more electrical signals in an electrical systemprovides information on the operating conditions of the system, asubsystem, or one or more components in the system. For example, anelectrical sensor may be used in control systems in manufacturing andindustrial applications. In such applications, an electrical sensor maybe used to monitor equipment status, to detect process variations, andto ensure safety of personnel. In addition, an electrical sensor may beused to control pumps, compressors, heaters, conveyors, and otherelectrically powered devices.

Some electrical sensors are equipped with an alarm that is activatedupon the detection of certain operation conditions. The problem withpresent electrical sensors is that the electrical sensors have a limiteddynamic range. In other words, the present electrical sensors arelimited to a narrow range between the minimum and the maximum valuesthat can be measured. As such, present electrical sensors are limited tospecific applications or systems that have to be specifically designedto accommodate the limited range of electrical sensors.

The high cost of the systems and its individual components as well asthe high power used for operating the systems require that the system beshut down to ensure the safety of the equipment and the technician whenadjustments are made. In addition, the use of an electrical sensor atthe upper and lower ends of a selected operating range createsreliability and accuracy problems. For example, operating an electricalsensor too close to its minimum rated value will not accurately measurevalues. There is a similar problem operating an electrical sensor tooclose to the upper limit of an operating range. Because of the problemof accurately monitoring currents at or near the extremes of anoperating range, the safety of equipment and personnel may bejeopardized. Further, the limited operating range of an electricalsensor restricts the use to specific systems or applications. Inaddition, once the electrical sensors have been manually adjusted, thepresent electrical sensors must be recalibrated. The recalibrationrequires shutting a system down to adjust manually the electricalsensor, and turning the system back on to verify that the sensor hadbeen adjusted properly. This is repeated until the electrical sensor isproperly configured. Alternatively, the electrical sensor can becalibrated off site but the system still must be shut down to reinstallthe electrical sensor and must again be verified it is configuredproperly, which includes turning the system back on and if necessaryshutting it down again to reconfigure the electrical sensor. Such aprocess of adjusting and recalibrating present electrical sensorscreates extended down time for a system and adds to the cost of runningthe system.

SUMMARY

An electrical sensor is described. The electrical sensor including anelectrical signal input configured to receive an electrical signal, analarm, one or more inputs configured to set a configuration valuecorresponding to one or more indicators on the electrical sensor, andmonitor. The monitor is coupled with the electrical signal input, thealarm, and the one or more inputs. Further, the monitor is configured todetermine a characteristic of the electrical signal received on theelectrical signal input. And, the monitor is configured to activate thealarm based on the configuration value set by the one or more inputs andthe characteristic of the electrical signal.

Other features and advantages of embodiments of the present inventionwill be apparent from the accompanying drawings and from the detaileddescription that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention are illustrated by way of exampleand not limitation in the figures of the accompanying drawings, in whichlike references indicate similar elements and in which:

FIG. 1 illustrates a block diagram of a current sensor according to anembodiment;

FIG. 2 illustrates a block diagram of a voltage sensor according to anembodiment;

FIG. 3 illustrates a block diagram of a power sensor according to anembodiment;

FIG. 4 illustrates a diagram of a burden resistor circuit for anelectrical sensor according to an embodiment;

FIG. 5 illustrates a diagram of a monitor circuit for an electricalsensor according to an embodiment;

FIG. 6 illustrates a top view of a diagram of an electrical sensorincluding one or more configuration inputs according to an embodiment;

FIG. 7 illustrates a perspective view of a diagram of an electricalsensor according to an embodiment;

FIG. 8 is a flow diagram of a method for monitoring a signal includingselecting a resistance based on a magnitude of a signal according to anembodiment;

FIG. 9 is a flow diagram of a method for configuring a monitor includingconfiguring a monitor to select a resistance based on a magnitude of asignal according to an embodiment;

FIG. 10 is a flow diagram of a method for monitoring a signal includingselecting a resistance based on a position of a switch according to anembodiment; and

FIG. 11 is a flow diagram of a method for configuring a monitorincluding configuring a monitor to select a resistance based on aposition of a switch according to an embodiment.

DETAILED DESCRIPTION

Embodiments of an electrical sensor are described. In particular, anelectrical sensor is described that is configured to operate over a widedynamic range. In addition, embodiments of an electrical sensor areconfigured to enable setting a trip point of an alarm based on visualindicators without the need to calibrate the electrical sensor or verifythe setting. According to an embodiment, an electrical sensordynamically adjusts its operating ranged based on the set value of atrip-point setting. For another embodiment, an electrical sensordynamically adjusts its operating range based on the measured magnitudeof an electrical signal, such as, a current level, a voltage leveland/or a power level. As such, embodiments of the electrical sensor canoperate over a wide dynamic range. In other words, embodiments of theelectrical sensor may be configured and may adapt to measure theelectrical characteristic of a signal over a large range of values.

In addition to providing the benefit of being able to operating over alarge range of values, embodiments of the electrical sensor offer thebenefit of not needing to be manually recalibrated when configurationadjustments are made. The electrical sensor, according to embodiments,includes user inputs, such as configuration inputs, to select the valueof one or more settings such as the trip point for an alarm and thedelay time of the alarm based on indicators located on the electricalsensor. As such, a user may select the desired setting without the needto recalibrate or to verify that the configuration settings are at thedesired value. This reduces the labor necessary to install or configuresuch a device. Thus, the features of embodiments of the electricalsensor provide ease of use, cost savings, and time savings over priorart sensors.

Embodiments of an electrical sensor include, but are not limited to, acurrent sensor, a voltage sensor, a power sensor, and other sensors formeasuring or determining characteristics of an electrical signal.Examples of such characteristics of an electrical signal include, butare not limited to, magnitude of a current or a voltage, polarity,average magnitude of a current or a voltage during a period of time,peak magnitude of a current or a voltage over a period of time, minimummagnitude of a current or a voltage during a period of time, or otheraspects of an electrical signal. Such electrical sensors include, butare not limited to, automation sensors, industrial sensors, and controlsensors. According to an embodiment an electrical sensor includes anelectrical signal input configured to receive an electrical signal tomonitor. Examples of an electrical signal input includes, but are notlimited to, a core, a voltage transformer, a resistive shunt, and othermethods to electrically couple with an electrical conductor. FIG. 1illustrates a block diagram of a current sensor according to anembodiment. Current sensor 102, according to an embodiment, includes acore 104. For an embodiment, a core 104 is made from a magneticallypermeable material. For example, a core 104 may be made fromferromagnetic metals, such as iron, ferromagnetic compounds, or othermaterial having a magnetic permeability. According to an embodiment, acore 104 is configured to form a toroid or other shape such that thecore 104 defines a sensing aperture 106. A core 104 may be any shapethat acts to guide magnetic fields generated by an electrical conductorlocated in the sensor aperture 106 defined by the core 104.

A core 104, according to an embodiment, is configured such that anelectrical conductor may pass through a sensing aperture 106. For someembodiments, a core 104 may be a solid core. That is, the core 104 isone piece such that an electrical conductor can be threaded through asensor aperture 106. Another embodiment includes a core 104 that is asplit core, such that the core 104 may be separated to allow anelectrical conductor to be placed within a sensor aperture 106.

A current in an electrical conductor is known to generate a magneticfield. A core 104 acts to magnify a magnetic field generated by anelectrical conductor situated in a sensing aperture 106. According to anembodiment, a core 104 may be a wire-wound core. Such a wire-wound coremay be used to sense or measure alternating current (“AC”) in anelectric conductor. For such an embodiment, an electrical conductorgenerates an alternating magnetic field. A core 104 acts to magnify analternating magnetic field generated by an electrical conductor. Thealternating magnetic field confined in the core 104 generates a currentin the wire wound around the wire-wound core. This current can then beused to measure or determine characteristics of a current in anelectrical conductor passing through a sensor aperture 106.Characteristics of an electrical signal that can be measured ordetermined include, but are not limited to, frequency, harmonics, orother characteristics of the electrical signal that can be derived froma current value.

According to an embodiment, the wire-wound core in combination with anelectrical conductor passing through a sensor aperture 106 acts as atransformer. As such, the current generated in the wire wound around thewire-wound core is proportional to the current in the electricalconductor according to principles known in the art with regards totransformers. Thus, a current in the electrical conductor passingthrough the sensor aperture 106, a primary current, may be determinedusing the corresponding current generated in the wire wound around thewire-wound core, a secondary current. The primary current may bedetermined by multiplying the secondary current by a multiplicationconstant. The multiplication constant is determined, as is known in theart, by the characteristics of a core and a number of windings aroundthe core. Alternatively, a multiplication constant may be determinedempirically. For example, a primary current, can be generated in anelectrical conductor passing through a sensor aperture 106 and thecorresponding secondary current generated in the wire wound around thewire-wound core may be measured. As such, a multiplication constant maybe used that is equal to or based on the ratio of the primary current tothe secondary current.

For some embodiments, a core 104 may include a hall-effect sensor. Acore 104 including or coupled with a hall-effect sensor is used tomeasure or determine a current, either AC or direct current (“DC”), inan electrical conductor passing through a sensor aperture 106. Asdescribed above, a core 104 acts to magnify the magnetic field generatedby the electrical conductor. The magnetic field confined within the core104 passes through the hall-effect sensor which generates a voltage thatmay be used to measure or determine characteristics of the current inthe electrical conductor passing through a sensor aperture 106 usingtechniques known in the art.

As illustrated in FIG. 1, a current sensor 102 includes a burdenresistor(s) 108 coupled with a core 104. According to an embodiment, aburden resistor(s) 108 is a circuit that includes one or more resistors.The one or more resistors are configured such that the resistance of theburden resistor(s) circuit may be changed. For some embodiments, one ormore resistors may be electrically coupled with the circuit through oneor more switches or relays. For such an embodiment, one or more switchesmay be used to add one or more resistors in series to add moreresistance to the circuit. According to another embodiment, the one ormore switches may be used to add one or more resistor in parallel toreduce the resistance of the circuit.

The embodiment illustrated in FIG. 1 also includes a monitor 109. For anembodiment, a monitor 109 is a circuit configured to determine themagnitude of a current in an electrical conductor passing through asensor aperture 106. A monitor 109 includes one or more control signals,according to an embodiment. One or more control signals, according to anembodiment, are coupled with one or more switches included with a burdenresistor(s) 108. According to an embodiment, a monitor 109 is configuredto use one or more control signals to activate one or more switches toadd one or more resistors to a circuit of burden resistor(s) 108 as thesensed or the determined magnitude of the current in the electricalconductor increases. For another embodiment, a monitor 109 is configuredto use one or more control signals to activate the one or more switchesto add one or more resistors to a circuit of a burden resistor(s) 108 asthe sensed or the determined magnitude of the current in the electricalconductor decreases. A monitor 109, according to an embodiment, may beconfigured to use to activate one or more switches of a burdenresistor(s) 108 based on an average value of the determined magnitude ofthe current over a period of time. According to an embodiment, one ormore control signals may be a voltage, a current, a bit stream, or othersignal that can be used to activate a switch.

A burden resistor(s) 108, according to an embodiment, may also includeother components in the circuit. For example, a burden resistor(s) 108may include, but is not limited to, diodes, capacitors, amplifiers,rectifiers or other components to further condition a signal. Accordingto an embodiment, a burden resistor(s) 108 coupled with a wire-woundcore includes, but is not limited to, a rectifier, such as a half-waverectifier, full-wave rectifier, or other type of rectifier as is knownin the art. As such, a burden resistor(s) 108 generates an output signalconditioned for monitor 109 to determine the magnitude of the current inthe electrical conductor passing through a sensor aperture 106,according to an embodiment. The output signal generated by a burdenresistor(s) 108, according to an embodiment, may include a current or avoltage that corresponds to the current in the electrical conductor.

A monitor 109 may also include a conditioning circuit to conditioning asignal received from a burden resistor(s) 108. The conditioning circuitmay include components including, but not limited to, amplifiers,diodes, resistors, capacitors or other components used alone or incombination to shape, transform, or otherwise alter a signal. For someembodiments, a monitor 109 may include a conditioning circuit inaddition to or instead of one or more components in burden resistor(s)108 for signal conditioning. According to an embodiment including awire-wound coil, a monitor 109 includes one or more components that actas a current-to-voltage convertor to transform a current output signalfrom a burden resistor(s) 108 into a voltage. This voltage can then beused by a monitor 109 to determine the current in the electricalconductor passing through a sensing aperture 106.

For an embodiment, a monitor 109 includes a conditioning circuit thatincludes components to scale a signal received from a burden resistor(s)108. For example, the conditioning circuit may expand a voltage range orcurrent range of the signal received from a burden resistor(s) 108.Another example includes a conditioning circuit that includes componentsto compress a voltage range or current range of a signal.

According to an embodiment, a monitor 109 generates one or more outputs114. One such output 114 includes generating a current output signalthat corresponds to the current in the electrical conductor threadedthrough a sensor aperture 106. According to an embodiment, monitor 109may generate a current output signal from the output signal from aburden resistor(s) 108 using one or more conditioning circuits such asthose described herein. For an embodiment, a monitor 109 generates acurrent output that corresponds to the determined magnitude of a currentin an electrical conductor passing through a sensor aperture 106.Another embodiment includes a voltage output that corresponds to thedetermined magnitude of a current in an electrical conductor passingthrough a sensor aperture 106.

A monitor 109 may also generate a digital output signal, according tosome embodiments. Such a digital output signal may include informationformatted into one or more bits. For an embodiment, one or more bits maybe combined to correspond to one or more binary numbers. According to anembodiment, a monitor 109 is configured to convey information about acurrent in an electric conductor passing through a sensor aperture 106and/or information determined from the current. Examples of suchinformation include, but are not limited to, characteristics of thecurrent such as magnitude, polarity, average magnitude during a periodof time, peak magnitude over a period of time, minimum magnitude duringa period of time, or other aspects of the current. Examples ofinformation determined from the current include, but are not limited to,frequency, harmonics, or other characteristics that can be determinedfrom a current.

As illustrated in FIG. 1, a monitor 109 is coupled with an alarm 110.According to an embodiment, an alarm 110 is a circuit configured togenerate an indication that the current in an electrical conductorpassing through a sensor aperture 106 is at or has passed a threshold.According to an embodiment, monitor 109 determines a threshold is met oris passed if the magnitude of a current in the electrical conductorpassing through the sensor aperture 106 is greater than or equal to aset threshold value. Upon such a determination the monitor activates analarm 110, according to an embodiment. A monitor 109 may also activatean alarm 110 upon determining that the magnitude of a current in theelectrical conductor is at a threshold value or less than the thresholdvalue, for an embodiment.

An alarm 110 may include, but is not limited to, a visual indicator, anaudible indicator, and an electrical indicator. Examples of a visualindicator include, but are not limited to, an LED, a display, a lamp andother visual indicators that can be visually perceived. Audibleindicators may include, but are not limited to, a buzzer, a chime, abell, and other indictors audibly perceived. Examples of an electricalindicator include, but are not limited to, generating a voltage or acurrent, activating a relay, switching a voltage or current from onelevel to another, driving a signal line to a voltage level or currentlevel, and other indications that can be detected electrically.

For an embodiment, an alarm 110 may be an electrical signal used as acontrol signal. For example, an alarm 110 may be used to as part of acontrol system. As such, the alarm 110 may be used to stop, start, orcontrol the rate of a process or system. According to an embodiment, oneor more outputs 114 may be used as a part of control system. Forexample, a current output that corresponds to a current passing througha sensor aperture 106 may be used to control the rate of a process orsystem.

For an embodiment, current sensor 102 may include one or more inputs112. One or more inputs 112, according to an embodiment, may be coupledto a monitor 109. An input(s) 112, such as a configuration input, may beconfigured to adjust the operation of a current sensor 102, according toan embodiment. For an embodiment, one or more configuration inputsinclude one or more adjustments to configure the operation of a currentsensor 112. According to an embodiment, one or more configuration inputsare configured to select a threshold value or a trip-point value for analarm 110. One or more configuration input may also select a delayvalue. For an embodiment, a delay value configures a period of time acurrent sensor 102 will delay the activation of an alarm after athreshold value or a trip-point value is met or passed. An input(s) 112includes, but is not limited to, dials, switches, keypads, communicationinterfaces, or other interfaces.

According to an embodiment, a monitor 109 is configured to use one ormore control signals to activate one or more switches included in aburden resistor(s) 108 based on a value selected by one or more inputs112. For an embodiment, a monitor 109 is configured to activate one ormore switches included in a burden resistor(s) 108 based on input(s) 112configured to select a trip-point value for an alarm 110. As such,monitor 109 is configured to determine a value set by input(s) 112 usedto select a trip-point value. Based on the determined trip-point value,a monitor 109 activates one or more switches to configure the resistancevalue for a burden resistor(s) 108, according to an embodiment.

FIG. 2 illustrates a voltage sensor 212 according to an embodiment. Asillustrated in FIG. 2, an embodiment of a voltage sensor 212 includes avoltage transformer 214. A voltage transformer 214, according to anembodiment, is configured to receive an input voltage signal 213. Theinput voltage signal 213, according to an embodiment, is voltage formonitoring and may be a DC, an AC, or a three-phase voltage signal.According to an embodiment, a voltage transformer 214 is configured toconvert an input voltage signal 213 to another voltage. For anembodiment, a voltage transformer 214 is a step-down transformer. Such astep-down transformer is configured to transform the input voltagesignal 213 to a lower voltage that corresponds to the input voltagesignal 213. Another embodiment includes a step-up transformer totransform the input voltage signal 213 to a higher voltage thatcorresponds to the input voltage signal 213. A voltage transformer 214may be any type of voltage transformer, such as an electromagneticvoltage transformer.

According to an embodiment, a voltage transformer 214 is anelectromagnetic transformer implemented using a wire-wound transformer,as is known in the art. For example, a voltage transformer 214 may be awire-wound core, as described herein, including an input voltage signal213 coupled with a primary winding wound around a magnetically permeablematerial, such as those described herein. The wire-wound core includes asecondary winding wound around the magnetically permeable material suchthat the transformer generates a second voltage proportional to theinput voltage signal 213 on the secondary winding, as is known in theart. For such an embodiment, the secondary voltage is proportional andmay be determined using a multiplication constant, as described herein.For an embodiment, the secondary voltage corresponds to the ratio of thenumber of turns in the second winding to the number of turns in theprimary winding, as is known in the art. As such, the secondary voltagewould be equal to an input voltage signal 213 multiplied by the numberof turns in the secondary winding divided by the number of turns in theprimary winding, according to an embodiment. For another embodiment, amultiplication constant may be determined empirically by generating aninput voltage signal 213 having known characteristics and measuring thecharacteristics of the secondary voltage, similar to techniquesdescribed herein with regard to current. An embodiment includes avoltage transformer 214 configured to generate an output current that isproportional to the input voltage signal 213, for example by usingtechniques described herein for converting a voltage to a current.According to an embodiment, a voltage transformer 214 includes ahall-effect sensor, as described herein, when the voltage transformer214 is configured to receive a DC input voltage signal. A voltage sensor212 is configured to measure or determine an input voltage signal 213from 0 volts to 600 volts, according to an embodiment. Anotherembodiment includes a voltage sensor 212 configured to measure an inputvoltage signal 213 from 0 volts to 150 volts. Yet another embodimentincludes a voltage sensor 212 configured to measure an input voltagesignal 213 greater than 600 volts. As such, one skilled in the art wouldunderstand embodiments of a voltage sensor 212 include those configuredto measure an input voltage signal 213 over any range of voltages.

For some embodiments, a voltage sensor 212 includes a burden resistor(s)216 coupled with a voltage transformer 214. Burden resistor(s) 216 isconfigured according to embodiments including, but not limited to, thosedescribed herein. As such, an embodiment of a burden resistor(s) 216includes one or more resistors configured such that a resistance of theburden resistor circuit may be changed, for example, by using techniquesdescribed herein. For some embodiments, a burden resistor(s) 216 may becoupled to a voltage transformer 214 through one or more components,such as those described herein. In addition, a burden resistor(s) 216may, according to an embodiment, include components other than resistivecomponents, such as those described herein. An output signal generatedby a burden resistor(s) 216, according to an embodiment, may include acurrent or a voltage that corresponds to an input voltage signal 213.

The embodiment of a voltage sensor 212 as illustrated in FIG. 2 alsoincludes a monitor 218 coupled with a burden resistor(s) 216. A monitor218 may be configured according to embodiments described herein. Assuch, a monitor 218, according to an embodiment, may include aconditioning circuit, such as those described herein. For an embodiment,a monitor 218 is configured to receive an output voltage from a burdenresistor(s) 216. According to an embodiment, a monitor 218 is configuredto determine the magnitude of an input voltage signal 213 using anoutput voltage from a burden resistor(s) 216, for example, by usingtechniques described herein.

A monitor 218 is configured to generate one or more outputs 224, such asusing techniques described herein. For example, a monitor 218 maygenerate a current output signal from an output signal from a burdenresistor(s) 216 using one or more conditioning circuits such as thosedescribed herein. For an embodiment, a monitor 218 generates a currentoutput that corresponds to a determined magnitude of the input voltagesignal 213, for example, by using techniques described herein. One ormore outputs 224 may include one of or a combination of a voltagesignal, a current signal, and a digital signal that corresponds to theinput voltage signal 213 that is generated by monitor 218, such as usingtechniques described herein.

As in the embodiment illustrated in FIG. 2, a monitor 218 is coupledwith an alarm 220. An alarm 220, according to an embodiment, is acircuit configured to generate an indication that an input voltagesignal 213 is at or has passed a threshold, for example, by usingtechniques described herein. As such, an embodiment includes a monitor218 configured to activate an alarm 220 upon determining the magnitudeof an input voltage signal 213, such as using techniques describedabove. An alarm 220, according to an embodiment, may include any of theindicators or electrical signals as described herein. For example, anembodiment includes a relay, such as those described herein, that isconfigured to be activated by a monitor 220, using techniques describedherein.

FIG. 2 also illustrates an embodiment including one or more inputs 222coupled with a monitor 218, such as those described herein. For example,an embodiment includes one or more inputs 222, such as one or moreconfiguration inputs, to configure an operation of a voltage sensor 212.According to an embodiment, one or more inputs 222 are configured toselect one of or a combination of a trip-point value, a threshold value,and a delay value for alarm 220, for example, by using techniquesdescribed herein. One or more inputs 222 include those described herein,such as dials, switches, keypads, communication interfaces, or otherinterfaces.

An embodiment of a voltage sensor 212 includes a monitor 218 configuredto change a resistance of a burden resistor(s) 216 through one or morecontrol signals, using techniques described herein. For example, amonitor 218 is configured to activate or select one or more switchesusing one or more control signals based on a determined value of aninput voltage signal 213, for example, by using techniques describeherein. Another embodiment, includes a voltage sensor 212 including amonitor 218 configured to change a resistance of a burden resistor(s)216 based on a value set by one or more inputs 222, using techniquesdescribed herein. One example includes, a monitor 218 configured todetermine a trip-point value selected by one or more inputs 222 andbased on the determined value using one or more control signals toconfigured the resistance of a burden resistor(s) 216 using techniquesdescribed herein.

FIG. 3 illustrates an embodiment of a power sensor 224 according to anembodiment. A power sensor 224, according to an embodiment, includes acore 226 configured to define a sensing aperture 228. Such a core 226includes cores as described herein for sensing or measuring a current inan electrical conductor passing through a sensing aperture 228. For someembodiments, a power sensor 224 includes a coil burden resistor(s) 230coupled with a coil 226, such as using techniques described herein. Foran embodiment, a core 226 may be external to power sensor 224 and may beelectrically coupled with a coil burden resistor(s) 230, for example,through one or more electrical conductors. Coil burden resistor(s) 230,according to an embodiment, is configured such as other burdenresistor(s) described herein. As such, an embodiment of a coil burdenresistor(s) 230 includes one or more resistors configured such thatresistance of a burden resistor circuit may be changed, for example, byusing techniques described herein. For some embodiments, burdenresistor(s) 230 may be coupled to a core 226 through one or morecomponents, such as those described herein. In addition, coil burdenresistor(s) 230 may, according to an embodiment, include componentsother than resistive components, such as those described herein. Anoutput signal generated by a coil burden resistor(s) 230, according toan embodiment, may include a current or a voltage that corresponds to acurrent in an electrical conductor passing through a sensing aperture228.

According to an embodiment as illustrated in FIG. 3, a power sensor 224includes a voltage transformer 232. A voltage transformer 232, accordingto an embodiment, is configured to receive an input voltage signal 233,such as described herein. As illustrated in FIG. 3, an embodiment of apower sensor 224 includes a voltage transformer 232 coupled with avoltage transformer burden resistor(s) 234. For an embodiment, a voltagetransformer 232 may be external to power sensor 224 and may beelectrically coupled with a voltage transformer burden resistor(s) 234,for example, through one or more electrical conductors. A voltagetransformer burden resistor(s) 234 may be configured according to otherburden resistor(s) described herein.

As such, an embodiment of a voltage transformer burden resistor(s) 234includes one or more resistors configured such that resistance of theburden resistor circuit may be changed, for example, by using techniquesdescribed herein. As described above, voltage transformer burdenresistor(s) 234 may be coupled to a voltage transformer 232 through oneor more components, such as those described herein. In addition, avoltage transformer burden resistor(s) 234 may, according to anembodiment, include components other than resistive components, such asthose described herein. The output signal generated by a voltagetransformer burden resistor(s) 234, according to an embodiment, mayinclude a current or a voltage that corresponds to an input voltagesignal 233.

An embodiment of a power sensor 224 as illustrated in FIG. 3 alsoincludes a monitor 236 coupled with a coil burden resistor 230 and avoltage transformer burden resistor(s) 234. A monitor 236 may beconfigured according to an embodiment of an electrical sensor asdescribed herein. As such, a monitor 236, according to an embodiment,may include a conditioning circuit, such as those described herein. Foran embodiment, a monitor 236 is configured to receive a coil outputvoltage from a coil burden resistor(s) 236 and a transformer outputvoltage from a voltage transformer burden resistor(s) 234. According toan embodiment, a monitor 236 is configured to determine a magnitude ofan input signal voltage 233 using a transformer output voltage, forexample, by using techniques described herein. Monitor 236, for anembodiment, is also configured to determine a magnitude of a current inan electrical conductor passing through a sensing aperture 228 usingtechniques as described herein.

A monitor 236, according to an embodiment, is configured to generate oneor more outputs 224, for example, by using techniques described herein.For example, a monitor 236 may generate one of or a combination of afirst current output signal based on an output signal from a coil burdenresistor(s) 230 and a second current output signal based on an outputsignal from a voltage transformer burden resistor(s) 234. According toan embodiment, a monitor 236 may generate one or more output signalsusing one or more conditioning circuits such as those described herein.For an embodiment, a monitor 236 generates a current output thatcorresponds to a determined magnitude of an input voltage signal 233,for example, by using techniques described herein. A monitor 236,according to an embodiment, also generates a current output thatcorresponds to a determined magnitude of a current in an electricalconductor passing through a sensing aperture 228, for example, by usingtechniques described herein.

For an embodiment, monitor 236 is configured to determine a power levelbased on an input voltage signal 223 and a current in an electricalconductor passing through a sensor aperture 228. A monitor 236,according to an embodiment is configured to determine a power levelbased on a determined magnitude of a current in an electrical conductorand a determined magnitude of an input voltage signal 233. For anembodiment, monitor 236 is configured to determine a magnitude of powerby multiplying a determined magnitude of a current in an electricalconductor by a determined magnitude of an input voltage signal 233 thatcorresponds to the determined current according to Joule's law. Oneskilled in the art would appreciate a power sensor 224 may be configuredto use one or more other values to determine a power level usingcalculation methods based on combining Joule's law and Ohm's law. Assuch, a monitor 236, according to an embodiment, is configured togenerate a current output that corresponds to the determined magnitudeof power, for example, by using techniques described herein. Inaddition, one or more outputs 242 may include one of or a combination ofa voltage signal, a current signal, and a digital signal thatcorresponds to one or more of the determined values generated by amonitor 236, such as using techniques described herein.

As in the embodiment illustrated in FIG. 3, a monitor 236 is coupledwith an alarm 238. An alarm 238, according to an embodiment, is acircuit configured to generate an indication that a determined value,such as a determined voltage, a determined current, and/or a determinedpower, is at or has passed a threshold, for example, by using techniquesdescribed herein. As such, an embodiment includes a monitor 234configured to activate an alarm 238 based upon determining a magnitudeof one or more of the determined values, such as using techniquesdescribed herein. An alarm 238, according to an embodiment, may includeany of the indicators or electrical signals as described herein. Forexample, an embodiment includes a relay, such as those described herein,that is configured to be activated by a monitor 236, using techniquesdescribed herein.

FIG. 3 also illustrates an embodiment including one or more inputs 240coupled with a monitor 236, such as those described herein. For example,an embodiment includes one or more inputs 240, such as one or moreconfiguration inputs, to configure an operation of a power sensor 224.According to an embodiment, one or more inputs 240 are configured toselect one of or a combination of a trip-point value, a threshold value,and a delay value for alarm 238, for example, by using techniquesdescribed herein. One or more inputs 240 include those described herein,such as dials, switches, keypads, communication interface, or otherinterfaces.

An embodiment of a power sensor 224 includes a monitor 236 configured tochange a resistance of one or both of a voltage transformer burdenresistor(s) 234 and coil burden resistor(s) 230 through one or morecontrol signals, using techniques described herein. For example, amonitor 236 is configured to activate one or more switches to configurea resistance for a voltage transformer burden resistor(s) 234 using oneor more control signals based on a determined value of an input voltagesignal 233, for example, by using techniques describe herein. Similarly,a monitor 236, according to an embodiment, is configured to activate oneor more switches to configure a resistance for a coil burden resistor(s)230 using one or more control signals based on a determined value of acurrent, for example, by using techniques describe herein.

Another embodiment, includes a power sensor 224 including a monitor 236configured to change a resistance of one of or a combination of a coilburden resistor(s) 230 and a voltage transformer burden resistor(s) 234based on a value set by one or more inputs 242, using techniquesdescribed herein. One example includes, a monitor 236 configured todetermine a trip-point value selected by one or more inputs 234 andbased on the determined trip-point value using one or more controlsignals to configure a resistance of one of or a combination of a coilburden resistor(s) 230 and a voltage transformer burden resistor(s) 234using techniques described herein.

According to an embodiment, a power sensor 224 is configured todetermine or derive other information based on one of or a combinationof a determined value of a current and a determined value of an inputvoltage signal 233. Examples of information determined by a power sensorinclude, but are not limited to, power dissipation, average power duringa period of time, minimum power during a period of time, maximum powerduring a period of time, or other information that may be determined oneof or a combination of current values and voltage values. For anembodiment, an electrical sensor, such as a current sensor, a voltagesensor, and a power sensor, may be configured to store one or moredetermined values in a memory. Such determined values may be accessed byone or more outputs based on a command or a signal received on one ormore inputs according an embodiment of an electrical sensor. Inaddition, an embodiment of an electrical sensor may include powercomponents configured to power one or more components used in theelectrical sensor.

FIG. 4 illustrates a block diagram of a burden resistor circuit 201 forimplementing a burden resistor of an electrical sensor according to anembodiment. For such an embodiment, resistive elements 202 a-c arecoupled with each other in parallel. Resistive elements 202 a-c include,but are not limited to, one of or a combination of one or more fixedresistors, one or more potentiometers, and one or more rheostats. Assuch, resistive element 202 a, for example, may be a single fixedresistor or a combination of one or more fixed resistors and apotentiometer to achieve a resistance R1 or R2. For an embodiment, thevalues of the resistive elements 202 a-c are chosen to minimize theamount of heat generated by the resistive elements 202 a-c when such asensor is in use.

According to an embodiment, resistive elements 202 a-c are coupled withone or more relays 204. The relays 204 are configured to switchresistive elements 202 a-c in or out of the burden resistor circuit 201to change the total resistance of the circuit. In other words, therelays 204 are used to electrically connect or disconnect resistiveelements 202 a-c to the circuit to change the overall resistance of thecircuit.

As illustrated in FIG. 4, a relay(s) 204 includes one or more controlsignals 206. For embodiments, each relay includes one or more controlsignals 206. Other embodiments include a plurality of relays 204 usingthe same control signals 206 such as a parallel or serial bus. Accordingto an embodiment, relay(s) 204 are coupled with a monitor throughcontrol signals 206. As such, a monitor uses the one or more controlsignals 206 to switch or to activate one or more relays 204 to connector disconnect the resistive elements 202 a-c to the circuit. For anembodiment, burden resistor circuit 201 is configured to have threeresistance levels. Other embodiments include burden resistor circuit 201with any number of resistance levels. As such, a monitor may use one ormore relays to switch among the one or more resistance levels to changethe total resistance of the circuit.

For an embodiment, each resistance level corresponds to a range ofcurrent, voltage, and/or power magnitudes. For an embodiment of acurrent sensor or a power sensor using three resistance levels, thefirst resistance level is for measuring a current having a magnitudeless than 150 amperes, the second resistance level is for measuring acurrent having a magnitude of 150 amperes up to 300 amperes, and thethird resistance level is for measuring current levels greater than 300amperes. According to an embodiment, a burden resistor(s) for anelectrical sensor is configured such that the total resistance of thecircuit is equivalent to approximately 14 ohms when the first resistivelevel is selected, equivalent to approximately 7 ohms when the secondresistance level is selected, and equivalent to approximately 2 ohmswhen the third level is selected. Such an embodiment is exemplary andother embodiments include using any number of resistance levels toconfigure an electrical sensor to operate over any range of currentmagnitudes.

For an embodiment, an electrical sensor such as a current sensor or apower sensor may be configured to measure current magnitudes over arange of 40 amperes to 200 amperes. According to another embodiment, acurrent sensor or a power sensor may be configured to measure currentover a range of 60 amperes to 1200 amperes. For yet another embodiment,a current sensor or a power sensor may be configured to measure currentof a range of 0 to 1200 amperes. Other embodiments include a currentsensor or a power sensor configured to measure a current above 1200amperes. As such, embodiments of a current sensors and a power sensormay be configured to measure a current in an electrical conductor over avariety of ranges. Similarly, a voltage sensor may include a burdenresistor circuit 201 configured to operate over many different ranges ofvoltage magnitudes.

A burden resistor circuit 201 also includes, according to an embodiment,input signal lines 208 a-b to couple with a core or a voltagetransformer. For an embodiment, burden resistor circuit 201 is coupledwith a core or a voltage transformer through a rectifier, as describedherein. A further embodiment includes burden resistor circuit 201coupled with a core or a voltage transformer through a rectifier andother components for conditioning a signal received from a core. Theembodiment illustrated in FIG. 4 also includes output signal lines 210a-b coupled with a monitor. As described herein, output signal lines 210a-b may be coupled with a monitor through one or more conditioningcircuits. According to an embodiment, output signal lines 210 a-b arecoupled with a monitor through a root-mean-square converter configuredto convert the output signal generated by a burden resistor circuit 201to a root-mean-square voltage signal. Output signal lines 210 a-b,according to an embodiment, may be a voltage signal or a current signalthat is proportional to the input signal received on input signal lines208 a-b.

For an embodiment, resistive elements 202 a-c are configured such thatthe voltage of output signal lines 210 a-b varies from approximately 0to 1 volt. Another embodiment includes resistive elements 202 a-cconfigured such that the voltage of output signal lines 210 a-b variesbetween approximately 0 to 2.5 volts. Yet another embodiment includesresistive elements 202 a-c configured such that the voltage of outputsignal lines 210 a-b varies from approximately 2.5 to 5 volts. Oneskilled in the art would appreciate that output signal lines 210 a-b maybe designed to have any range of values by varying the value ofcomponents in a circuit including the values of resistive elements 202a-c.

FIG. 5 illustrates a block diagram of a monitor circuit for anelectrical sensor according to an embodiment. A monitor includes,according to an embodiment, a monitor circuit that includes a processor302. A processor 302 may include, but is not limited to, one or more ofa microprocessor, a microcontroller, a digital signal processor, andother processing devices. The processor 302 according to an embodimentis coupled with a digital-to-analog converter 304. For an embodiment,processor 302 receives an output signal from one or more burdenresistors as described herein on one or more burden signal inputs 306.

The processor 302, according to an embodiment, determines a magnitude ofa current in an electrical conductor passing through a sensing apertureby comparing a value of one or more burden signal inputs 306 to areference value. Similarly, a processor 302, according to an embodiment,determines a magnitude of an input voltage signal by comparing a valueof the one or more burden signal inputs 306 to a reference value.According to an embodiment, a burden signal input 306 is a voltage thatis proportional to a magnitude of a current in an electrical conductorpassing through a sensor aperture. Another embodiment includes burdensignal inputs 306 that is a voltage that is proportional to a magnitudeof an input voltage signal. For an embodiment, the burden signal input306 is in a range from approximately 0 to 5 volts. For anotherembodiment, a burden signal input 306 is in a range from approximately0.5 to 4.5 volts. Yet another embodiment includes a burden signal input306 in a range from approximately 0 to 1 volt.

According to an embodiment, a processor 302 includes ananalog-to-digital converter that converts an analog voltage signalgenerated by a burden resistor circuit and received through of one ormore burden signal inputs 306 into a binary number that corresponds tothe analog voltage signal. A binary number includes a series of bitsthat represent or correspond to a value. An embodiment may also includean analog-to-digital converter that is external to a processor 302. Insuch an embodiment, the binary number is transmitted to a processor 302.According to an embodiment, the processor is configured to multiply abinary number by a multiplication constant. Such a multiplicationconstant includes, but is not limited to, multiplication constantsdetermined using techniques described herein. For an embodiment, theresult of multiplying the binary number by the multiplication constantdetermines the value of at least one of a magnitude of a current, amagnitude of a voltage, or a magnitude of power depending on whether abinary number corresponds to a measured current, a measured voltage or ameasured power value, respectively. According to an embodiment, aprocessor 302 is configured to multiply a determined current magnitudeby a determined voltage magnitude to determine a power magnitude.

According to an embodiment, a processor 302 is configured to use abinary number to determine the magnitude of a current in an electricalconductor passing through a sensor aperture by referencing a currentmagnitude lookup table stored in a memory. For an embodiment, aprocessor 302 is configured to use a binary number to determine amagnitude of an input voltage signal by referencing a voltage magnitudelookup table stored in a memory. A processor 302, according to anembodiment references a current magnitude lookup table entrycorresponding to a received binary number which includes a currentmagnitude value that corresponds to a magnitude of the current in anelectrical conductor passing through a sensor aperture. For anembodiment, a processor 302 may be configured to use a similar techniquefor determining a voltage magnitude or power magnitude. For anembodiment, the lookup table is stored in memory internal to theprocessor 302. According to another embodiment, lookup table is storedin an external memory.

According to an embodiment, a processor 302 is coupled with adigital-to-analog converter 304. A processor 302 outputs a determinedmagnitude value for a received binary number to a digital-to-analogconverter 304. A determined magnitude value may be a magnitude of acurrent, an input voltage signal, or power depending on the type ofinput a binary number corresponds to, according to an embodiment. For anembodiment, a magnitude value is outputted as a serial bit stream.According to an embodiment, a processor 302 also provides a clock todigital-to-analog converter 304 that corresponds to the serial bitstream for clocking bits into a digital-to-analog converter 304. Adigital-to-analog converter 304 generates an output voltage signal thatcorresponds to a received digital magnitude value.

As such, a monitor circuit generates an output voltage signal thatcorresponds to a magnitude of at least one of an input voltage signal,power, and a current in an electrical conductor passing through a sensoraperture. According to an embodiment, a monitor circuit is configured togenerate an output voltage signal that varies from approximately 0 to 5volts. Another embodiment includes a monitor circuit that is configuredto generate an output voltage signal that varies from approximately 0 to10 volts. Other embodiments may be configured to generate an outputvoltage signal that varies over other voltage ranges.

For an embodiment, a monitor circuit includes a voltage-to-currentconverter 308 to convert an output voltage signal from adigital-to-analog converter 304 into a corresponding output currentsignal. A voltage-to-current converter, according to an embodiment, isconfigured to generate an output current signal from approximately 4milliamperes to 20 milliamperes, such that each value of the outputcurrent signal corresponds to a magnitude of at least one of an inputvoltage signal, power, and a current in an electrical conductor. Foranother embodiment the range for the output current signal isapproximately 0 milliampere to 20 milliamperes. According to anotherembodiment, the range for an output current signal is approximately 1milliampere to 15 milliamperes. Other embodiments are configures to havean output current signal operate over a different range of currentvalues. For an embodiment, a change in an output current signalgenerated by a monitor is proportional to a change in a signal measuredor sensed by an electrical sensor.

For an embodiment, a processor 302 also selects or activates one or morerelay(s) or switches in a burden resistor circuit based on a value of aburden signal input received on 306. As described above, a processor 302may convert a burden signal input 306 received into a binary number.This binary number, according to an embodiment, is used to determinewhich relays to activate. For an embodiment, processor 302 references arelay-configuration lookup table that includes the settings of therelays that correspond to a received binary number. Therelay-configuration lookup table may be stored in memory internal to aprocessor 302 or external to a processor 302. According to someembodiments, a magnitude lookup table and a relay-configuration lookuptable are the same lookup table that has two entries for a given valueof a burden signal input 306. One entry in the lookup table is amagnitude value and one entry is for a relay configuration.

Based on the relay configuration retrieved from a lookup table, aprocessor 302 generates a relay output 312 to select among resistorelements in a burden resistor circuit. According to an embodiment, arelay output 312 may include one or more signal lines. A relay output312 includes one signal line for each relay or switch used in a burdenresistor circuit, according to an embodiment. According to anembodiment, a processor 302 generates a voltage on a signal line toactivate or select a relay. For example, a 5 volt signal is generated onrelay output 312. Another embodiment includes a processor 302 pullingrelay output 312 to ground to activate a relay. Yet another embodimentincludes relay output 312 configured as a bus such that a processor 302sends a command to an address assigned to a relay or switch to activateit.

A processor 302, according to an embodiment, is also configured toreceive one or more inputs, such as one or more configuration inputs,that indicate a threshold value and/or a delay value to configure analarm. According to an embodiment, a processor 302 is coupled with oneor more inputs, as described above, through one or more input signallines 313. For an embodiment, one or more configuration inputs coupledwith a processor 302 through one or more input signal lines 313 areconfigured to generate a signal that corresponds to a position of aswitch. For example, a configuration input includes a switch that variesits resistance as its position changes, such as a potentiometer. Assuch, a configuration input is configured to generate a signal thatcorresponds to a value based on a resistance of the switch.

According to an embodiment, one or more configuration inputs areconfigured to generate an input current value that corresponds to aposition of a configuration input. For another embodiment, aconfiguration input is configured to generate an input voltage valuethat corresponds to a position of a configuration input. According to anembodiment, a configuration input is configured to generate a voltage ora current on one or more input signal lines 313 that correspond to aposition or setting of a configuration input. A processor 302, accordingto an embodiment, determines the position or setting of theconfiguration input by accessing an input-value lookup table at alocation that corresponds to a voltage or a current value on one or moreinput signal lines 313. An input-value lookup table may be stored ininternal memory to processor 302 or memory external to processor 302.

According to another embodiment, the one or more configuration inputsare binary-coded decimal switches. For such an embodiment, abinary-coded decimal switch is configured to output a binary number thatcorresponds to the position of the switch. For such an embodiment, aprocessor 302 is configured to receive a binary number of one or moreconfiguration inputs using techniques described herein. For anembodiment, a processor 302 generates a relay output 312 to select amongresistor elements in a burden resistor circuit based on one or moreinputs. According to an embodiment, one or more binary-coded decimalswitches are used to set a trip-point value. As such, a processor 302 isconfigured to receive a binary number of the one or more binary-codeddecimal switches and to generate a relay output 312 that corresponds tothe binary number.

For an embodiment of an electrical sensor including three resistivelevels in a burden resistor(s), a processor 302 is configured todetermine if a binary number that corresponds to a set trip-point valuefalls within a range of magnitudes that correspond to the firstresistance level, the second resistance level, or a third resistancelevel. Based on this determination, a processor 302 selects theresistance level of a burden resistor circuit using techniques describedherein.

According to an embodiment, a processor 302 determines if a binarynumber is within a range of magnitudes by comparing the binary number toa minimum and/or maximum magnitude of at least one range thatcorresponds to a resistance level of a burden resistor circuit. If thebinary number is determined to be between a minimum and a maximummagnitude for a range that corresponds to a resistance level, aprocessor 302 selects that resistance level. According to an embodiment,if a binary number is determined to be equal to a minimum magnitude of arange that corresponds to a resistance level, a processor 302 isconfigured to select a resistance level that corresponds to a range ofmagnitudes less than that minimum magnitude value. If a binary signal isdetermined to be equal to a maximum value of a range that corresponds toa resistance level, according to an embodiment, a processor 302 isconfigured to select a resistance level that corresponds to a range ofmagnitudes greater than that maximum value. According to an embodiment,a minimum and/or a maximum value for each range is stored in a lookuptable stored in a memory. As such, a processor 302, according to anembodiment, accesses a memory to determine a minimum and/or a maximumvalue for a range used to compare a binary number for configuring aresistance level of a burden resistor circuit.

For an embodiment, a processor 302 is configured to compare one or morebinary signals to a burden signal input 306. For an embodiment, a burdensignal input 306 is a binary number, as described herein. As such, aprocessor 302 is configured to compare a binary number from a burdensignal input 306 and one or more binary signals from one or moreconfiguration input that set a configuration value of an electricalsensor, including, but not limited to, a trip-point value, a thresholdvalue, and a delay value. According to an embodiment, if a processor 302determines that a binary number that corresponds to one or more burdensignal inputs 306 is greater than the binary number that corresponds toa set trip-point value, the processor 302 activates an alarm usingtechniques described herein. For an embodiment, if a processor 302determines that a binary number that corresponds to one or more burdensignal inputs 306 is less than the binary number that corresponds to aset trip-point value, the processor 302 activates an alarm usingtechniques described herein.

Another embodiment includes an electrical sensor configured to set aminimum and a maximum threshold values using techniques describedherein. For such an embodiment, one or more configuration inputs maycorrespond to a minimum threshold value set using one or more switches.Similarly, one or more configuration inputs may correspond to a maximumthreshold value set using one or more switches. As such, according to anembodiment, a processor 302 is configured to determine if a binarynumber that corresponds to one or more burden signal inputs 306 iswithin a range set by a minimum and a maximum threshold values. If aprocessor 302, according to an embodiment, determines a binary numberthat corresponds to one or more burden signal inputs 306 is within arange set by a minimum and a maximum threshold values, the processor 302may activate an alarm. Alternatively, an embodiment includes a processor302 configured to activate an alarm if the processor 302 determines abinary number that corresponds to one or more burden signal inputs 306is outside a range set by a minimum and a maximum threshold values, theprocessor may activate an alarm. An embodiment also includes comparing abinary number that corresponds to one or more burden input signals 306,as described herein, after the binary number is multiplied by amultiplication constant using techniques descried herein.

According to an embodiment, an electrical sensor includes aconfiguration input for each place value of a setting, such as athreshold value, a trip-point value, or delay value. For an embodiment,a processor 302 is coupled with three configuration inputs to set athreshold value, a trip-point value, or a delay value: one for the tensplace value, one for the hundreds place value, and one for the thousandsvalue. An embodiment includes at least a configuration input configuredto set a delay value for an alarm.

A processor 302, according to an embodiment, is also coupled with analarm such as an alarm relay 314. A processor 302 is configured toactivate an alarm relay based on the configuration inputs that set atrip-point value, a threshold value and/or delay value, as describedherein. A processor 302 activates an alarm relay 314 upon determiningconditions are met based on configuration inputs by generating an alarmrelay signal. Such an alarm relay signal may be a voltage, a current, orother signal type. According to an embodiment, processor 302 activatesan alarm relay 314 by generating a 5 volt alarm relay signal. Alarmrelay 314, according to an embodiment, generates an alarm signal 316that may be used by a control system to indicate that a current level, avoltage level, or a power level in an electrical conductor has passed acertain threshold, as described herein.

FIG. 6 illustrates a block diagram of an electrical sensor 402 includingone or more configuration inputs according to an embodiment. Anelectrical sensor 402, according to an embodiment, includes aconfiguration panel 404 including a plurality of configuration inputsfor configuring the operation of an electrical sensor 402. An electricalsensor 402 includes indicators 406, according to an embodiment.According to an embodiment, a configuration panel 404 includes aplurality of configuration inputs such as selectors 408 a-d. Selectors408 a-d, according to an embodiment, set the value of a configurationsetting. For example, selector 408 a illustrated in the FIG. 4 is usedto set the delay value and selectors 408 b-d are used to set thetrip-point or threshold value for an alarm. A configuration panel 404also includes indicators 406 that correspond to a value or a settingthat the selectors are set to, according to an embodiment. Indicators406 are labeled on configuration panel 404 according to an embodiment.An indicator 406 may be any alphanumeric character that represents avalue or a setting. Such an indicator 406 may be etched on, drawn on,printed on, or otherwise affixed to an electrical sensor 402. As such, auser would set the value by moving a selector 408 a-d to point to theindicator of the value desired. Thus, the value of a selector 408 a-d isset and an electrical sensor 402 determines the value based on aposition of a selector 408 a-d using techniques described herein.

FIG. 7 illustrates a perspective view of an electrical sensor 502 thatincludes a coil for measuring a current according to an embodiment. Anelectrical sensor 502, according to an embodiment includes aconfiguration panel 404 to set the operational characteristics of theelectrical sensor, as described herein. For an embodiment, sensoraperture 503 is configured to accept an electrical conductor 506 throughelectrical sensor 502 to enable sensing or measuring a current in theelectrical conductor 506. An electrical sensor 502 also includes outputsas described herein, according to an embodiment. For an embodiment, anelectrical sensor 502 includes one or more connectors 504 for connectingone or more outputs to other equipment such as a control system ormonitor system. In addition, one or more connectors 504, according to anembodiment, include inputs for receiving an input voltage signal tocouple with a voltage transformer as described herein. For anembodiment, one or more connectors are configured to receive a voltageused to provide power to components used in an electrical sensor.Connectors 504 include, but are not limited to, keyed connectors,terminal blocks, posts, plug and socket connectors, and other connectorsfor making an electrical connection.

FIG. 8 is a flow diagram of a method for monitoring a signal includingselecting a resistance based on a magnitude of a signal according to anembodiment. At block 602, the method includes monitoring a signal usingtechniques as described herein. At block 604, the method determines amagnitude of a signal using techniques described herein. The magnitudeof a signal corresponding to at least one of a voltage level, a currentlevel, or a power level. The method also selects one or more resistorsbased on the magnitude of the signal using techniques as describedherein. In addition, a method generates an output based on aconfiguration setting that corresponds to one or more indicator at block608 using techniques described herein. According to an embodiment, aconfiguration setting includes, but is not limited to, a trip-pointvalue, a delay value, and a threshold value. As described herein, avalue of a configuration setting is determined based on a position of aswitch relative to one or more indicators. For some embodiments, themethod generates an output based on a plurality of configurationsettings.

FIG. 9 is a flow diagram of a method for configuring a monitor includingconfiguring a monitor to select a resistance based on a magnitude of asignal according to an embodiment. According to an embodiment, themethod includes, at block 702, configuring a monitor to determine amagnitude of a signal using techniques described herein. At block 704,the method configures a monitor to select resistors based on themagnitude of a signal using techniques described herein. The method alsoincludes configuring the monitor to activate an alarm based on themagnitude of a signal and a position of one or more configuration inputsrelative to one or more indicators using techniques described herein.

FIG. 10 is a flow diagram of a method for monitoring a signal includingselecting a resistance based on a position of a switch according to anembodiment. At block 802, the method includes monitoring a signalaccording to an embodiment, using techniques described herein. Themethod, at block 804 determines a position of one or more switches usingtechniques described herein. As described herein, a position of one ormore switches corresponds to a value of a configuration settingincluding, but not limited to, a trip-point value, a delay value, and athreshold value. At block 806, the method selects one or more resistorsbased on a position of one or more switches, using techniques describedherein. According to an embodiment, the method selects one or moreresistors based on a position of one or more switches that set atrip-point value. The method, at block 808, generates an output based onone or more configuration settings that corresponds to one or moreindicators. As described herein, a value of a configuration setting isdetermined based on a position of a switch to one or more indicators.For an embodiment, the method generates an output, such as an alarm,using techniques as described herein.

FIG. 11 illustrates a flow diagram of a method for configuring a monitorincluding configuring a monitor to select a resistance based on aposition of a switch according to an embodiment. At block 902, themethod includes configuring a monitor to determine a position of one ormore switches using techniques as described herein. According to anembodiment, a monitor, such as embodiments described herein, may beincluded in a voltage sensor, a current sensor, or a power sensor. Themethod, at block 904, configures a monitor to select one or moreresistors based on a position of one or more switches as describedherein. According to an embodiment, a monitor may select one or moreresistors of a burden resistor(s) of an electrical sensor as describedherein. At block 906, the method configures a monitor to activate analarm based on a magnitude of a signal and a position of one or moreswitches relative to one or more indicators as described herein.According to an embodiment, configuring a monitor includes one of or acombination of programming a processor, loading instructions or codeinto a processor or memory, connecting components, and otherwisearranging components.

In the foregoing specification, specific exemplary embodiments of theinvention have been described. It will, however, be evident that variousmodifications and changes may be made thereto. The specification anddrawings are, accordingly, to be regarded in an illustrative rather thana restrictive sense.

What is claimed is:
 1. An electrical sensor comprising: an electricalsignal input configured to receive an electrical signal; an alarm; oneor more inputs configured to set a configuration value corresponding toone or more indicators on the electrical sensor; and a monitor coupledwith said electrical signal input, said alarm, and said one or moreinputs, said monitor configured to determine a characteristic of saidelectrical signal received on said electrical signal input and saidmonitor configured to activate said alarm based on said configurationvalue set by said one or more inputs and said characteristic of saidelectrical signal.
 2. The electrical sensor of claim 1, wherein saidmonitor includes a processor coupled with a plurality of resistors, saidprocessor configured to select at least one of said plurality ofresistors responsive to said characteristic of said electrical signal.3. The electrical sensor of claim 1, wherein said alarm is a controlsignal.
 4. The electrical sensor of claim 1, wherein said one or moreinputs includes a selector configured to set a tens place value of saidconfiguration value corresponding to said one or more indicators on theelectrical sensor.
 5. The electrical sensor of claim 4, wherein said oneor more inputs includes a selector configured to set the hundreds placevalue of said configuration value corresponding to said one or moreindicators on the electrical sensor.
 6. The electrical sensor of claim5, wherein said one or more inputs includes a selector configured to setthe thousands place value of said configuration value corresponding tosaid one or more indicators on the electrical sensor.
 7. The electricalsensor of claim 5, wherein said one or more inputs includes a selectorconfigured to set the thousands place value of said trip pointcorresponding to said one or more indicators on the electrical sensor.8. The electrical sensor of claim 4 further comprising a delay inputconfigured to select a delay value corresponding to one or moreindicators on the electrical sensor.
 9. The electrical sensor of claim5, wherein said monitor is coupled with said delay input and saidmonitor is configured to delay activation of said alarm for a period oftime corresponding to said delay value.
 10. The electrical sensor ofclaim 1, wherein said electrical signal input includes a core configuredto define a sensing aperture and said core is configured to generate acurrent that corresponds to said electrical signal.
 11. The electricalsensor of claim 10 further comprising a hall-effect sensor coupled withsaid core.
 12. The electrical sensor of claim 10 further comprising anoutput coupled with said monitor, said characteristic is a determinedcurrent of said electrical signal input, and said monitor is configuredto generate an output signal corresponding to a magnitude of a currentof said determined current of said electrical signal.
 13. The electricalsensor of claim 1, wherein said electrical signal input is a voltagetransformer configured to generate a first voltage that corresponds tosaid electrical signal, said characteristic is a determined voltage ofsaid electrical signal input, and said monitor is configured to generatean output signal corresponding to a magnitude of said determined voltageof said electrical signal input.
 14. The electrical sensor of claim 12,wherein said electrical signal input further includes a voltagetransformer configured to generate a first voltage that corresponds tosaid electrical signal, said characteristic is a determined voltage ofsaid electrical signal input, and said monitor is configured to generatean output signal corresponding to a magnitude of said determined voltageof said electrical signal input.
 15. The electrical sensor of claim 1further comprising a plurality of burden resistors coupled with saidmonitor, said monitor further is configured to select among saidplurality of burden resistors based on said configuration valuecorresponding to one or more indicators on the electrical sensor.
 16. Anapparatus for measuring one or more electrical characteristiccomprising: an electrical signal input configured to receive anelectrical signal; a plurality of burden resistors coupled with saidelectrical signal input; at least one input configured to set aconfiguration value corresponding to one or more indicators on theapparatus; and a monitor circuit coupled with said plurality of burdenresistors and coupled with said at least one input, said monitorconfigured to determine a characteristic of said electrical signal, andsaid monitor configured to select at least one burden resistor of saidplurality of burden resistors.
 17. The apparatus of claim 16 furthercomprising an alarm circuit, wherein said configuration value is a trippoint corresponding to said one or more indicators, and said monitor isfurther configured to activate said alarm based on said configurationvalue selected by said at least one input.
 18. The apparatus of claim16, wherein said monitor includes a processor coupled with saidplurality of resistors, said processor configured to select said atleast one of said plurality of resistors based on said determinedcharacteristic of said electrical signal.
 19. The apparatus of claim 18,wherein said processor is configured to select at least one of saidplurality of resistors through one or more relays configured to add saidplurality of resistors in parallel.
 20. The apparatus of claim 16,wherein said monitor is configured to select at least one burdenresistor of said plurality of burden resistors based on saidconfiguration value corresponding to said one or more indicators. 21.The apparatus of claim 16, wherein said at least an input includes afirst selector configured to set a tens place value of saidconfiguration value that corresponds to said one or more indicators anda second selector configured to set a hundreds place value of saidconfiguration value that corresponds to said one or more indicators. 22.A method comprising: configuring a monitor of an electrical sensor todetermine a characteristic of an electrical signal; configuring saidmonitor to select from a plurality of resistors coupled with saidmonitor based on said characteristic of an electrical signal; andconfiguring said monitor to activate an alarm coupled with said monitorbased on said characteristic of an electrical signal and a position ofone or more inputs relative to one or more indicators.
 23. The method ofclaim 22 wherein configuring said monitor of said electrical sensor todetermine a characteristic of said electrical signal includesconfiguring said monitor to determine a current of said electricalsignal.
 24. The method of claim 22 wherein configuring said monitor ofsaid electrical sensor to determine a characteristic of said electricalsignal includes configuring said monitor to determine a voltage of saidelectrical signal.
 25. The method of claim 22 wherein configuring saidmonitor of said electrical sensor to determine a characteristic of saidelectrical signal includes configuring said monitor to determine a powerof said electrical signal.
 26. A process for sensing a characteristic ofan electrical signal, the process comprising: monitoring said electricalsignal received on an electrical signal input; determining acharacteristic of said electrical signal; selecting one or moreresistors based on said characteristic of said electrical signal; andgenerating an output corresponding to said characteristic of saidelectrical signal.